3. The Estimate Technique The estimate technique is used when we can't get a control group and we can't get any actual participant performance data from human resources (HR) or the business to use the attribution technique. Here, you can still do some isolation, but you need to rely solely on estimates. First, ask participants how much they've improved a specific business metric over the past months " ... because of the training. " Second, you'll take that very rough estimate of their performance improvement (which is typically inflated) and adjust it down for error and increased confidence.https://trainingindustry.com/continuing-professional-development/certificates/measuring-the-impact-of-training-certificate/